Quaternary Arsenides <i>AM</i><sub>1.5</sub><i>Tt</i><sub>0.5</sub>As<sub>2</sub> (<i>A</i> = Na, K, Rb; <i>M</i> = Zn, Cd; <i>Tt</i> = Si, Ge, Sn): Size Effects in CaAl<sub>2</sub>Si<sub>2</sub>- and ThCr<sub>2</sub>Si<sub>2</sub>-Type Structures
Bibliographic record
Abstract
Ten quaternary arsenides AM(1.5)Tt(0.5)As2 (A = Na, K, Rb; M = Zn, Cd; Tt = Si, Ge, Sn) have been prepared by stoichiometric reactions of the elements at 600-650 °C. Seven of them (NaZn(1.5)Si(0.5)As2, NaZn(1.5)Ge(0.5)As2, NaZn(1.5)Sn(0.5)As2, NaCd(1.5)Sn(0.5)As2, KZn(1.5)Sn(0.5)As2, KCd(1.5)Sn(0.5)As2, RbCd(1.5)Sn(0.5)As2) adopt the trigonal CaAl2Si2-type structure (Pearson symbol hP5, space group P3m1, Z = 1, a = 4.0662(3)-4.4263(7) Å, c = 7.4120(5)-8.4586(14) Å), whereas the remaining three (KZn(1.5)Si(0.5)As2, KZn(1.5)Ge(0.5)As2, RbZn(1.5)Ge(0.5)As2) adopt the tetragonal ThCr2Si2-type structure (Pearson symbol tI10, space group I4/mmm, Z = 2, a = 4.0613(10)-4.1157(5) Å, c = 14.258(3)-14.662(2) Å). Both structure types contain anionic [M(1.5)Tt(0.5)As2] slabs that are built from edge-sharing tetrahedra and that stack alternately with nets of A cations. A structure map delineates the formation of these structure types for AM(1.5)Tt(0.5)As2 as a function of simple radius ratios. Although these arsenides have charge-balanced formulations, band structure calculations on NaZn(1.5)Tt(0.5)As2 (Tt = Si, Ge, Sn) indicate that semimetallic behavior is predicted as a result of overlap of the valence and conduction bands.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.006 |
| Meta-epidemiology (narrow) | 0.009 | 0.010 |
| Meta-epidemiology (broad) | 0.008 | 0.003 |
| Bibliometrics | 0.002 | 0.007 |
| Science and technology studies | 0.003 | 0.006 |
| Scholarly communication | 0.004 | 0.006 |
| Open science | 0.008 | 0.006 |
| Research integrity | 0.006 | 0.010 |
| Insufficient payload (model declined to judge) | 0.001 | 0.007 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; both teacher heads agree on what is shown here.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".